#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ul;
typedef signed long long ll;
ul over = 1000000007;

int main(void)
{
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed;
  int h, w;
  cin >> h >> w;
  bool isb[h][w];
  int cnt = 0;
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      char c;
      cin >> c;
      isb[i][j] = (c=='#' ? true : false);
      if (isb[i][j]) cnt++;
    }
  }
  if (cnt%2==1) {cout << "NO" << endl; return 0;}
  for (int i = 0; i < h; ++i) {
    for (int j = 0; j < w; ++j) {
      if (i==0 && j==0) continue;
      int f_cnt = 0;
      bool hit[h][w];
      for (int k = 0; k < h; ++k) {
        for (int l = 0; l < w; ++l) hit[k][l] = false;
      }
      for (int k = 0; k < h; ++k) {
        for (int l = 0; l < w; ++l) {
          if (hit[k][l]) continue;
          if (isb[k][l] && i+k<h && j+l<w) {
            if (isb[i+k][j+l]) {
              f_cnt++;
              hit[i+k][j+l] = true;
            }
          }
        }
      }
      if (f_cnt == cnt/2) {
        cerr << i << " " << j << endl;
        cout << "YES" << endl;
        return 0;
      }
    }
  }
  cout << "NO" << endl;
  return 0;
}